Chapter Two, © Callie Clark, 2008

CHAPTER TWO

ORIENTING TO SINGLE FREQUENCIES, KEY JINGLE, CRUMPLING TIN FOIL, AND ULTRASONIC VOCALIZATION: SOUND-INDUCED ACTIVATION IN NORMAL AND HALOPERIDOL-TREATED RATS



ABSTRACT

Central dopaminergic pathways influence the ability of an animal to locate and respond appropriately to novel environmental stimuli. Correspondingly, lesions of the striatum produce deficits in orienting to sensory stimuli and prepulse inhibition deficits. The current study investigated the movements elicited by a range of auditory stimuli including key jingle, crumpling chip bag, ultrasonic vocalization (USV), and single frequencies across the rat hearing range. Saline- and haloperidol-treated rats were placed in an orienting chamber and filmed for orienting responses to novel sounds. A modified EWMN notation score and five-point cephalocaudal orienting scale described the orienting components of both groups. Results showed that key jingle and rat USV were most potent for evoking an orienting response, which was characterized by a characteristic three-stage motor response of Orient, Attend, and Disengage. Further, when responding to frequencies within a 22-kHz band, key jingle, or chip bag, the rat’s pinna and not eyes turned in the location of the sound source. These two observations highlight differences in detecting auditory stimuli that can be seen in the orienting phase alone, and provide insight into which sounds might work best as a “cue” for motor tasks.